Commonly-owned U.S. Pat. No. 4,642,833 to Stoltz, et al. (the “Stoltz Patent”), whose contents are incorporated herein in their entirety by this reference, discloses various valve assemblies useful for automatic swimming pool cleaners. These assemblies typically include flexible, generally tubular diaphragms surrounded by chambers, with the diaphragms interposed in the main fluid-flow paths through the cleaners. In response to variation in pressure internally and externally, the diaphragms contract and expand transversely along at least part of their lengths, thereby controlling fluid flow therethrough.
Mentioned in the Stoltz Patent is that versions of the diaphragms may have “substantially oval-shaped or diamond-shaped cross section . . . when a total fluid flow interruption is to be achieved.” See Stoltz Patent, col. 3, ll. 36-38. Also detailed in the Stoltz Patent is use of longitudinal ribs “along that part [of a diaphragm] which contracts to the greatest extent.” See id., col. 5, ll. 32-33. According to the Stoltz Patent, such ribs enable a diaphragm to contract to an X-shaped pattern depicted in FIG. 7 of the patent. See id. ll. 33-35.
Commonly-owned U.S. Pat. No. 4,742,593 to Kallenbach (the “Kallenbach Patent”), the contents of which also are incorporated herein in their entirety by this reference, discloses additional valve assemblies for use with automatic swimming pool cleaners. These assemblies too are generally tubular in shape and made of flexible material. As noted in the Kallenbach Patent:                The body [of the tubular valve] has an intermediate section between the ends that assumes a substantially collapsed condition over a segment thereof in absence of a pressure differential between the interior and exterior. The section preferably is collapsed transversely over a segment.        Along the collapsed segment, the body has diverging interior walls in the direction of water flow therethrough. The walls diverge from a substantially constant diameter that extends for a portion of the section adjacent the first end to a substantially constant, but larger, diameter that extends for a portion of the section adjacent the second end. Further, the divergence is a substantially linear function of the distance along the segment.See Kallenbach Patent, col. 1, ll. 28-42.        
U.S. Pat. No. 6,098,228 to Chang (the “Chang Patent”), entitled “Pool Cleaner Diaphragm Valve,” likewise addresses diaphragm-style valves and ancillary assemblies for automatic swimming pool cleaners. Apparently, however, these valves are of the type specified in the Kallenbach Patent. Indeed, according to the Chang Patent, this type of valve “is ideal” for the purposes described therein. See Chang Patent, col. 6, ll. 60-65.
Commonly-owned U.S. Patent Publication No. 2006/0054229 of van der Meijden, et al. (the “van der Meij den Publication”), whose contents are incorporated herein in their entirety by this reference, addresses further generally-tubular valve assemblies. Preferred embodiments of the assemblies include mouths divided into three parts. As stated in the van der Meij den Publication, this division “admits a larger through hole within the valves, in turn enabling larger debris to pass.” See van der Meijden Publication, p. 1, ¶ 0008.